Richard Fleischner, who directed the 1966 cult film Fantastic Voyage, would have been delighted with Bradley Nelson’s research: similar to the story in Fleischner’s film, Nelson wants to load tiny robots with drugs and manoeuvre them to the precise location in the human body where treatment is needed, for instance to the site of a cancer tumour. Alternatively, the tiny creatures could also be fitted with instruments, allowing operations to be performed without surgical intervention. The advantages compared with conventional treatments with drugs are clear: far more targeted therapy, and as a result, fewer side effects.